fix: do not render "value of stdout.lastframe() is undefined" if the output is an empty string

[petebacondarwin]

Fixes #2907

What this PR solves / how to test:

If the components passed to renderToString() resulted in an empty string, we were incorrectly converting that to a warning message. This message should only apply if there is a problem with rendering and it returns undefined.

To test run the following commands:

npx wrangler d1 create TEST_DB 
npx wrangler d1 execute TEST_DB --command "DROP TABLE IF EXISTS test_table"

You should not see the "value of stdout.lastframe() is undefined" message.

Author has included the following, where applicable:

• Tests D1 query execution is not possible to unit test - the WASM causes a segmentation fault in NodeJS.
• Changeset (Changeset guidelines)

Reviewer has performed the following, where applicable:

• Checked for inclusion of relevant tests
• Checked for inclusion of a relevant changeset
• Checked for creation of associated docs updates
• Manually pulled down the changes and spot-tested

[changeset-bot]

🦋 Changeset detected

Latest commit: 8f383e6

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
wrangler	Patch

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Click here if you're a maintainer who wants to add another changeset to this PR

[github-actions]

A wrangler prerelease is available for testing. You can install this latest build in your project with:

npm install --save-dev https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/4446793807/npm-package-wrangler-2912

You can reference the automatically updated head of this PR with:

npm install --save-dev https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/prs/2912/npm-package-wrangler-2912

Or you can use npx with this latest build directly:

npx https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/4446793807/npm-package-wrangler-2912 dev path/to/script.js

Additional artifacts:

npm install https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/4446793807/npm-package-cloudflare-pages-shared-2912

Note that these links will no longer work once the GitHub Actions artifact expires.

[codecov]

Codecov Report

Merging #2912 (8f383e6) into main (163dccf) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #2912      +/-   ##
==========================================
+ Coverage   74.06%   74.09%   +0.02%     
==========================================
  Files         167      167              
  Lines       10418    10418              
  Branches     2785     2785              
==========================================
+ Hits         7716     7719       +3     
+ Misses       2702     2699       -3     

Impacted Files	Coverage Δ
packages/wrangler/src/utils/render.ts	92.00% <100.00%> (ø)

... and 2 files with indirect coverage changes

[rozenmd]

Confirmed this fixes the issue via preview build

[Qxxxx]

I don't know if it stops statements excution. I have three slq commands in .sql file but only one statement is excuted.

🌀 Mapping SQL input into an array of statements
🌀 Parsing 3 statements
🌀 Executing on DB (DBID):
🚣 Executed 1 command in 0.01684001088142395ms
value of stdout.lastframe() is undefined

[JacobMGEvans]

Nice! We have had turning some things to ?? be a problem glad to see it fix stuff too lol